Alkylation-transalkylation process



Aug. 1o,- 1965 E', R, FENSKE 3,200,163

ALKYLATION-TRANSLKYLATION PROCESS Filed March l2, 1962 2 Sheets-Sheet l n S L n o f l )In a Q Q n. N it m g 4 E C A u n s v Q s 1 x 'n 2 l Q/ o( N+ NVEVTOR: Ellsworth l?. Fenska BY A T TOR/VEYS Aug. 10, 1965 E. R. FENsKE I ALKYLATION-TRANSALKYLATION PROCESS 2 Sheets-,Sheet 2 Filed March l2, 1962 gm ATTORNEY United States Patent Gftice 3,2%,163 Patented Aug. l0, i965 3,200,163 ALKYLA'HN-TRANSALKYLAHON PRCESS Eilsworth R. liensire, Palatine, Ell., assigner to Universal @il Products Company, Des Plaines, lll., a corporation of Delaware Filed Mar. 12, 1962, Ser. No. 173,936 9 tiairns. (Cl. 26o- 671) This invention relates to an improved process for the production of an aromatic compound, and more particularly relates to an improved process for the alkylation of an alkylatable aromatic compound with an olefinacting compound, and still more particularly relates to the alkylation of an aromatic hydrocarbon with an oleinic hydrocarbon which may be in combination with other gases which are unreactive at the process conditions utilized. Further, this invention relates to a combination process including the steps of alkylation, trans-alkylation and separation.

The principal object of this invention is to provide an improved process for the alkylation of alkylatable aromatic compounds with olefin-acting compounds in the presence of free and/or combined boron trifluoride. I have found that unusual problems are encountered in the commercial application of such processes due to trace quantities of Water encountered per se or as coordination compounds of boron tritluoride. These problerns are solved by the utilization of the process of the present invention, which process results in maximum yield of desired alkylated aromatic hydrocarbon and minimum loss of alkylating agent, alkylatable aromatic hydrocarbon and boron trifiuoride. A further object of this invention is to provide an improved process for the production of ethylbenzene, a desired chemical intermediate, which ethylbenzene is utilized in large quantities in dehydrogenation processes for the manufacture of styrene, one of the starting materials for the production of resins and some synthetic rubber. Another specific object of this invention is to produce alkylated aromatic hydrocarbons boiling Within the gasoline boiling range having high anti-knock value and which may be used as such or as a component of gasoline suitable for use in automobile and airplane engines. Still another object of this invention is a process for the production of cumene by the reaction of benzene with propylene, which cumene product is oxidized in large quantities to form curnene hydroperoxide Which is readily decomposed into phenol and acetone. Another object of this invention is to provide a process for the introduction of alkyl groups into aromatic hydrocarbons of high vapor pressure at normal conditions with minimum loss of said high vapor pressure aromatic hydrocarbons and maximum utilization thereof in the process. Still another object of this invention is an improved process in which molar excesses of aromatic hydrocarbons to be alkylated are utilized, and in which process the yield of monoalkylated aromatic hydrocarbon product is exceptionally high due to maximum consumption of polyalkylated aromatic hydrocarbon by-products in the process. The further object of maximum boron triiluoride utilization as a catalyst in this process, along with other objects of this invention, will be set forth hereinafter as part of the accompanying specification.

One embodiment of the present invention relates to an improved process for the production of an aromatic compound which comprises alkylating an allrylatable aromatic compound With an olefin-acting compound in the presence of a catalytic amount of boron tritluoride in an alkylation reaction zone containing a boron triiiuoride-modified substantially anhydrous inorganic oxide, commingling the eiuent of said alkylation zone with effluent from a transalkylation reaction zone as hereinafter set forth, passing the thus commingled effluents to a separation zone, separating from the separation zone unreacted aromatic compound substantially free of boron compound impurities, desired monoalkylated aromatic compound, higher molecular Weight polyalkylated aromatic compound and boron trifiuoride, recycling at least a portion of said unreacted aromatic compound to the alkylation zone, removing desired monoalkylated aromatic compound as product from the process, passing said polyalltylated aromatic compound in admixture With at least a portion of said unreacted aromatic compound and boron trifiuoride to a transalkylation zone containing boron triuoride-modied substantially anhydrous inorganic oxide and therein reacting the polyalkylated aromatic `compound with unreacted compound, and recycling the eiiluent therefrom to said commingling step as aforesaid.

Another embodiment of the present invention relates to an improved process for the production of an aromatic compound which comprises alkylating and alkylatablearomatic compound With an olen-acting compound in the presence of a catalytic amount of boron triiiuoride in an alkylation reaction zone containing a boron trifiuoride-modii'ied substantially anhydrous inorganic oxide, commingling the efliuent from said alkylation zone with effluent from a transalkylation reaction zone as hereinafter set forth, passing the thus commingled eiluents to a first fractionation column, taking as bottoms from said column desired monoalkylated aromatic compound in admixture with higher molecular weight polyalkylated aromatic compound, passing said admixturc to further fractionation in a second fractionation column, taking as overhead from said rst column unreacted aromatic compound and boron triiiuoride, separating said boron trifluoride from said unreacted aromatic compound, passing said unreacted aromatic compound to a stripper zone, countercurrently contacting said unreacted aromatic compound With stripping gas, passing stripped unreacted aromatic compound to a treating zone, treating said stripped unreacted aromatic compound, recovering unreacted aromatic compound substantially free of boron compound impurities, recycling at least a portion of said unreacted aromatic compound to the alkylation zone, passing the admixture of desired monoalkylated aromatic compound and undesired polyalkylated aromatic compound to a second fractionation column, removing overhead in said second fractionation column desired monoalkylated aromatic compound as product from the process, passing as bottoms from said second fractionation column polyalkylated aromatic compound and mixing the same with at least a portion of said unreacted aromatic compound and boron triuoride, passing said mixture to a transalkylation zone containing boron trifluoride-modiiied substantially anhydrous inorganic oxide and therein reacting the polyalkylated aromatic compound with unreacted aromatic compound, and recycling the effluent therefrom to said commingling step as aforesaid.

A further embodiment of the present invention relates t0 an improved process for the production of an aromatic compound ywhich comprises alkylating an alkylatable aromatic compound with an olefin-acting compound in the presence of a catalytic amount of boron trifluoride in an alkylation reaction zone containing a boron triuoridemodified substantially anhydrous inorganic oxide, cornmingling the effluent from said alkylation zone With effluent from a transalkylation reaction zone as hereinafter set forth, passing the thus commingled efliuents to a fractionation column, taking as bottoms from said column de- |sired monoalkylated aromatic compound in admixture with higher molecular weight polyalkylated aromatic compound, passing said admixture to further fractionation in a second fractionation column, taking as overhead from said first column boron triiiuoride, taking as sideeut from said first column unreacted aromatic compound, passing said unreacted aromatic compound to a treating zone, treating said unreacted aromatic compound, recovering unreacted aromatic compound substantially free of boron compound impurities, recycling at least a portion of said unreacted aromatic compound to the alkylation zone, passing the admixture of desired monoalkylatcd aromatic compound and undesired .polyalkylated aromatic compound to a second fractionation column, removing overhead in said second fractionation column desired .monoalkylated aromatic compound as product from the process, passing as bottoms from said second fractionation column lpolyalkylated aromatic compound and mixing the same with at least a portion of said unreacted aromatic compound and boron trifluoride to a transalkylation zone containing boron trifluoride-modified substantially anhydrous inorganic oxide and therein reacting the polyalkylated aromatic compound with unreacted aromatic compound, and recycling the effluent .therefrom to said commingling step as aforesaid.

A specific embodiment of the present invention relates to an improved process for the production of ethylbenzene which comprises alkylating benzene with ethylene in the presence of a catalytic amount of boron triuoride in an alkylation reaction zone containing a boron triiiuoridemodified substantially anhydrous alumina, commingling the effluent of said alkylation zone with efiiuent from a transalkylation reaction zone as hereinafter set forth, passing the thus commingled efliuents to a separation zone, separating from the separation zone unreacted benzene substantially free of boron compound impurities, desired ethylbenzene, higher molecular Weight polyethylbenzenes and boron .trifluoride, recycling at least a portion of said unreacted benzene to the alkylation zone, removing desired ethylbenzene as product from the process, passing said polyethylbenzenes in admixture with at least a portion of said unreacted benzene and boron trifiuoride to a transalkylation zone containing boron tritluoride-modified substantially anhydrous alumina and therein reacting the polyethylbenzenes with unreacted benzene, and recycling the effluent therefrom to said commingling step as aforesaid.

Other embodiments of the present invention will become apparent in considering the specification as hereinafter set forth.

This invention can be most clearly described and illustrated with reference to the attached drawings. While of necessity, ycertain limitations must be present in such schematic descriptions, no intention lis meant thereby to limit the generally broad scope of this invention. As stated hereinabove, the first step of the process of the present invention comprises alkylating an alkylatable aromatic compound with an olefin-acting compound in the presence of a catalytic amount of boron trifluoride in an alkylation reaction zone containing a boron triliuoride-modified substantially anhydrous inorganic oxide. In FIGURE l, this first step is represented as taking place in alkylation reaction zone 4 labeled alkylation. However, the mixture of boron tritiuoride, alkyltable aromatic compound, and olefin-acting compound must be furnished to this reaction zone. In the drawing, the boron tritluoride is represented as being furnished to reaction zone 4 through line 1. The olefin-acting compound is represented as being furnished to reaction zone 4 through line 2. The alkyltable aromatic compound is represented as being furnished to reaction zone 4 through line 3.

The olefin-acting compound, particularly olefin hydrocarbon, which may be charged to reaction zone 4 via line 2, may be selected from diverse materials including monoolefins, diolefins, polyolefins, acetylenic hydrocarbons, and also alcohols, ethers, and esters, the latter including alkyl halides, alkyl sulfates, alkyl phosphates, and various esters of carboxylic acids. The preferred olefin-acting compounds are olefinic hydrocarbons which comprise monooleiins containing one double bond per molecule and polyolefins which contain more than one double bond per molecule. Monoolefins which are utilized as olefin-acting compounds in the process of the present invention are either normally gaseous or normally liquid and include ethylene, propylene, l-butene, Z-butene, isobutylene, and higher molecular weight normally liquid oletins such as the various pentenes, hexenes, heptenes, oetenes and mixtures thereof, and still higher molecular Weight liquid olefins, the latter including various olen polymers having from about 9 to about 18 carbon atoms per molecule including propylene trimer, propylene tetramer, propylene pentamer, etc. Cycloolefins such as cyclopentene, methylcyclopentene, cyelohexene, methylcyelohexene, etc., may also be utilized. Also included within the scope of the olefin-acting compound are certain substances capable of producing olefinic hydrocarbons or intermediates thereof under the conditions of operation utilized in the process. Typical olefin-producing substances or olefin-acting cornpounds capable of use include alkyl halides capable of undergoing dehydrohalogenation to form olefinic hydrocarbons and thus containing at least 2 carbon atoms per molecule. Examples of such alkyl halides include ethyl iiuoride, n-propyl fluoride, isopropyl fluoride, n-butyl fluoride, isobutyl fiuoride, sec-butyl fluoride, tert-butyl liuoride, etc., ethyl chloride, n-propyl chloride, isopropyl chloride, n-butyl chloride, isobutyl chloride, sec-butyl chloride, tertbutyl chloride, etc., ethyl bromide, n-propyl bromide, isopropyl bromide, n-butyl bromide, isobutyl bromide, secbutyl bromide, tert-butyl bromide, etc. As stated hereinabove, other esters such as alkyl sulfates including ethyl sulfate, propyl sulfate, etc., and alkyl phosphates including ethyl phosphate, etc., may be utilized. Ethers such as diethyl ether, ethyl propyl ether, dipropyl ether, etc., are also included within the generally broad scope of the term olefin-acting compound and may be successfully utilized as alkylating agents in the process of this invention.

Olefin hydrocarbons, particularly normally-gaseous hydrocarbons, are olefin-acting compounds for use in the process of this invention and for passage by means of line 2 to reaction zone 4. The process of this invention may be successfully applied to and utilized for complete con- Version of olen hydrocarbons when these olefin hydrocarbons are present in minor quantities in various gas streams. Thus, the normally gaseous olefin for use in the process of this invention need not be concentrated. Such normally gaseous olefin hydrocarbons appear in minor quantities in various refinery gas streams, usually diluted with gases such as hydrogen, nitrogen, methane, ethane, propane, etc. These gas streams containing minor quantities of oletin hydrocarbons are obtained in petroleum refineries from various refinery installations including thermal cracking units, catalytic cracking units, thermal reforming units, eoking units, polymerization units, dehydrogenation units, etc. Such refinery gas streams have in the past often been burned for fuel value, since an economical process for the utilization of their olefin hydrocarbon content has not been available, or processes which have been suggested by the prior art utilized such large quantities of alkylatable aromatic compound that they have not been economically feasible. This is particularly true for refinery gas streams known as ofi-gas streams containing relatively minor quantities of olefin hydrocarbons such as ethylene. Thus, it has been possible to catalytically polyrneirze propylene and/ or butenes in the various refinery gas streams, but the olf-gases from such processes still contain the utilizable olefin hydrocarbon, ethylene. In addition to containing ethylene in minor quantities, these ofi-gas streams contain other olefin hydrocarbons, depending upon their source, including propylene and butenes. A reiinery off-gas ethylene stream may contain varying quantities of hydrogen, nitrogen, methane and ethane with the ethylene in minor proportion, while a refinery off-gas propylene stream is normally diluted with propane and contains the propylene in minor quantity, and a refinery off-gas butene stream is normally diluted With butanes and contains the butenes in minor quantities. A typical analysis in mol percent for utilizable refinery offgas from a catalytic cracking unit is as follows: nitrogen, 4.0%; carbon monoxide, 0.2%; hydrogen, 5.4%; methane, 37.8%; ethylene, 10.3%; ethane, 24.7%; propylene, 6.4%; propane, 10.7% 4and C., hydrocarbons, 0.5%. It is readily observed that the total olefin content of this gas stream is 16.7 mol percent and the ethylene content is even lower, namely, 10.3%. Such gas streams containing olefin hydrocarbons in minor or dilute quantities are particularly preferred alkylating agents within the broad scope of this invention. It is readily apparent that only the olefin content of such streams undergoes reaction at alkylation conditions of the process, and that the remaining gases free from olefin hydrocarbons are vented from the process. it is one of the features of this invention that the gases which do not react may be utilized in the separation zone as hereinafter described, or they may be vented from the process with minimum loss of boron trifiuoride and alkylatable aromatic compound due to their vapor pressure at the conditions of temperature and pressure utilized for ventmg the non-reactive gases.

The olefin-acting compound, acting as the alkylating agent, combines therewith in alkylation zone 4 alkylatable aromatic compound from line 3 with boron trrfiuonde combined therewith from line 1 as will be set forth hereinafter. Many aromatic compounds are utilizable as alkylatable aromatic compounds within the process of this invention. The preferred aromatic compounds are aromatic hydrocarbons, and the preferred aromatic hydrocarbons are monocyclic aromatic hydrocarbons, that is, benzene hydrocarbons. Suitable aromatic hydrocarbons include benzene, toluene, ortho-xylene, metaxylene, para-xylene, ethylbenzene, ortho-ethyltoluene, metaethyltoluene, para-ethyltoluene, 1,2,3-trimethylbenzene, 1,2,4- trimethylbenzene, 1,3,5-trimethylbenzene, normal propylbenzene, isopropylbenzene or cumene, normal butylbenzene, etc. drocarbons are also suitable as starting materials and include aromatic hydrocarbons such as are produced by the .alkylation of the aromatic hydrocarbons with olefin polymers. Such products are frequently referred to 1n the art as alkylate, and include hexylbenzenes, nonylbenzenes, dodecylbenzenes, pentadecylbenzenes, hexyltoluenes, nonyltoluenes, dodecyltoluenes, pentadecyltoluenes, etc. Very often alkylate is obtained as a high boiling fraction in which the alkyl group attached to the aromatic nucleus varies in size from about C9 to C18. Other suitable alkylatable aromatic hydrocarbons include those with two or more aryl groups such as diphenyl, diphenylmethane, triphenyl, triphenylmethane, fluorene, stilbene, etc. Examples of alkylatable aromatic hydrocarbons Within the scope of this invention utilizable as starting materials and containing condensed aromatic rings include naphthalene, alkyl naphthalenes, anthracene, phenanthrene, naphthacene, rubrene, etc. When the selected alkylated aromatic hydrocarbon is a solid, it may be heated by means not shown so that it passes as a liquid through line 3 as hereinafter described. Of the alkylatable aromatic hydrocarbons for use as starting materials in the process of this invention, the benzene hydrocarbons are preferred, and of the benzene hydrocarbons, benzene itself is particularly preferred.

As stated hereinabove, boron trifluoride is added to alkylation zone 4 conveniently by passage through line l. Boron trifiuoride is a gas, boiling point 101 C., melting point 126 C., and is somewhat soluble in most organic solvents. It may be and generally is utilized per se by mere passage thereof as a gas through line 1 so that it dissolves at least partially in the allrylatable aromatic compound passing into allrylation zone 4 via line 3. The boron trifiuoride may also be added as the Higher molecular weight alkyl aromatic hy- 6 solution of a gas in a suitable organic solvent. However, in the utilization of such solutions, care must be exercised so that the selective solvent is unreactive with the alkylating agent or normally gaseous olefin hydrocarbon utilized in the process. Furthermore, boron trifluoride complexes with many organic compounds, particularly those containing sulfur or oxygen atoms. These complexes, While utilizable as catalysts, are very stable and thus will interfere with the recoveiy of boron trifiuoride in the separation zone hereinafter set forth. Therefore, further limitation upon the selection of such a solvent is that it be free from atoms or groups which form complexes with boron trifiuor-ide. The amount of boron trifiuoride which is utilized is relatively small. lt has been found that the amount necessary can be conveniently expressed as grams of boron trifiuoride per gram mol of olefin-acting compound, preferably olefin. This amount of boron tritluoride will not contain more than 1.0 gram of boron tririuoride per gram mol of olefin utilized. When the amount of boron trifiuoride present in the alkylation zone is within the above expressed limit, substantially complete conversion of the olefin-acting compound is obtained even when the olefin-acting compound is present in what might seem to be minor or dilute quantities in the gas stream. Furthermore, a portion of boron triuoride then carries over from the alkylation reaction zone to the transalkylation reaction zone as hereinafter described wherein that amount will be utilized again, or in combination with further added boron trifiuoride, to cause the transalkylation reaction to go forward. Thus, double use of the originally added quantity of boron trifiuoride is obtained in this process.

Prior to passage to the alkylation zone, unreacted aromatic compound substantially free of boron compound impurities is combined with the alkylatable aromatic compound via lines 9 and 3 as hereinafter set forth. Recycled unreacted aromatic compound is available in the process since it is preferred to utilize a molar excess of alkylatable aromatic compound over olen-acting compound, preferably olefin. This, as disclosed in the prior art, has been found necessary to prevent side reactions from taking place such as for example, polymerization of the olefin-acting compound prior to reaction thereof with the alkylatable aromatic compound and to direct the reaction principally to monoalkylation. Any molar excess of alkylatable aromatic compound may be utilized, although best results are obtained when the alkylatable aromatic compound to olefin-acting compound molar ratio is from about 3:1 to about 20:1 or more. It is one of the features of this invention that unreacted aromatic compound substantially free of boron compound impurities is available for recycle to the aikylation reaction zone.

Alkylation zone 4 is of the conventional type with a boron trifluoride-modiiied inorganic oxide disposed therein in the reaction zone. The alkylation zone may be equipped with heat transfer means, baflies, trays, heating means, etc. The alkylation reaction zone is preferably of the adiabatic type and thus feed to the alkylation zone will preferably be provided with the requisite amount of heat prior to passage thereof to said alklation zone. As set forth hereinabove, the alkylation reaction zone is packed with a boron triiluoride-modified inorganic oxide. The inorganic oxide with which the zone is packed may be selected from among diverse inorganic oxides including alumina, silica, boria, oxides of phosphorous, titanium dioxide, zirconium dioxide, chromia, zinc oxide, magnesia, calcium oxide, silica-alumina, silica-magnesia, silica-alumina-magnesia, silica alumina-zirconia, chromia-alumina, alumina-boris., silica-zirconia, etc., and various naturally occurring inorganic oxides of various states of purity such as bauxite, clay (which may or may not have been previously acid treated), diatomaceous earth, etc. Of the abovementioned inorganic oxides, gamma-alumina and theta-alumina are most readily modified by boron trifiuoride, and

thus the use of one or both of these boron triuoride-modified aluminas is preferred. The modification of the inorganic oxide, particularly alumina, may be carried out prior to or simultaneous with the passage of the reactants containing boron tritiuoride to the reactor. The exact manner in which the inorganic oxides are modified by boron triuoride is not completely understood. However, it has been found that the modification is preferably carried out at a temperature at least as high as that selected for use in the particular zone, so that the catalyst in said Zone will not exhibit an activity induction period. If the inorganic oxide is modified prior to use, this modification may be carried out in situ in the reactor or in a separate catalyst preparation step. More simply, this modification is accomplished by mere passage of boron trifiuoride gas over a bed of the inorganic oxide maintained at the desired temperature. If the modification of the inorganic oxide with boron tritiuoride is carried out during the passage of the reactant thereover, the catalyst will exhibit an induction period and thus complete reaction of the alkylating agent with the alkylatable aromatic compound, and transalkylation of the recycled polyalkylated aromatic compounds will not take place for some hours, say up to 12 or more.

The conditions utilized in reaction zone 4 may be varied over a relatively wide range. Thus, the desired alkylation reaction in the presence of the above indicated catalyst may be effected at a temperature of from about or lower to about 300 C. or higher. The alkylation reaction is usually carried out at a pressure of from about substantially atmospheric, preferably from about to about 200 atmospheres or more. The pressure utilized is usually selected to maintain the alkylatable aromatic compound in substantially liquid phase. However, within the abovementioned temperature and pressure ranges, it is not always possible to maintain the olefin-acting compound in liquid phase. Thus, when utilizing a renery off-gas containing ethylene as the olefin-acting compound, the ethylene will be dissolved in the liquid phase alkylatable aromatic compound (and alkylated aromatic compound as formed) to the extent governed by temperature, pressure, and solubility considerations. However, a portion thereof will always be in the gas phase. The hourly liquid space velocity of the liquid through the alkylation zone may be varied over relatively wide range of from about 0.1 to about or more.

When the alkylation reaction has proceeded to the desired extent, preferably with 100% conversion of the olefin-acting compound, the products from the alkylation zone which may be termed alkylation zone effluent, pass from alkylation reaction zone 4 via line 5 to a commingling step, hereinafter described, to separation zone 6.

In separation zone 6, unreacted aromatic compound substantially free of boron compound impurities, desired monoalkylated aromatic compound, higher molecular weight polyalkylated aromatic compound and boron trifluoride are separated as hereinafter described with reference to FIGURES 2 and 3. At least a portion of said unreacted aromatic compound substantially free of boron compound impurities is recycled via lines 9 and 3 to akylation zone 4 and via lines 9 and 10 to transalkylation zone 13. Desired monoalkylated aromatic compound is removed as product from the process via line 15 from separation zone 6. Boron triiiuoride recovered from separation zone 6 is removed via line '7 where at least a portion of said boron triliuoride is returned to the separation zone and the remainder or net amount is passed via line 3 to lines 1 and 12 as hereinafter set forth. Polyalkylated aromatic compound is passed to transalkylation zone 13 from separation zone 6 Via line 11.

Transalkylation zone 13 is of the conventional type with a boron triuoride-modified inorganic oxide disposed therein in the reaction zone. The transalkylation zone may be equipped with heat transfer means, baffles, trays, heating means, etc. The transalkylation reaction zone is preferably of the adiabatic type and thus feed to the transalkylation zone will preferably be provided with the requisite amount of heat prior to passage thereof to said transalkylation zone. As set forth hereinabove, the transalkylation reaction zone is packed with a boron triiiuoridemodified inorganic oxide. The particular boron triiluoride-modified inorganic oxide is generally selected so that the same material is utilized in both the alkylation reaction zone and the transalkylation reaction zone. Since the conditions necessary for transalkylation are generally more severe than for alkylation, one effective means for increasing severity is by utilization of a bed of boron triiiuoride-modied inorganic oxide in transalkylation zone 13 of greater depth than was utilized as in the alkylation zone 4. By the utilization of such greater bed depth, one effectively decreases the liquid hourly space velocity of the combined feed therethrough and thus increases reaction zone severity. As was the case with the conditions utilized in the alkylation reaction zone, the conditions utilized in transalkylation reaction zone 13 may be varied over a relatively wide range, but, as set forth hereinabove, are usually of greater severity than prevail in the alkylation reaction zone. Various means other than increasing catalyst bed depth and decreasing liquid hourly space velocity may be utilized for increasing this reaction zone severity. For example, the mol concentration of boron trifluoride in transalkylation zone 13 may be greater than for alkylation zone 4 by passage of additional boron trifiuoride thereto via lines 1 and 12. Also, when the alkylation reaction zone and transalkylation reaction zone are separate as shown in the drawing, one may effectively increase the temperature by proper placement of heating means before each reactor. The transalkylation reaction may be effected at temperatures of from about to about 350 C. or higher and at a pressure of from about substantially atmospheric, preferably from about 15 to about 200 atmospheres. Here again, the pressure utilized is selected to maintain the alkylatable aromatic compound and polyalkylated aromatic compound in substantially liquid phase. Referring to the alkylatable aromatic compound, it is preferable to have present in the transalkylation reaction zone from about 1 to about 10 or more, sometimes up to 20, molar proportions per molar proportion of alkyl group in the polyalkylated aromatic hydrocarbon introduced therewith. The hourly liquid space velocity of the liquid through transalkylation zone 13 may be varied over a relatively wide range of from 0.1 to about 20 or more. The alkylatable aromatic cornpound to polyalkylated aromatic compound ratio in the transalkylation reaction zone can be varied independently of the alkylation reactor rates. When the transalkylation reaction has proceeded to the desired extent so that a sufficient quantity of polyalkylated aromatic compounds are converted to monoalkylated aromatic compounds by reaction with alkylatable aromatic compound, the gasfree products from transalkylation zone 13 are withdrawn through line 14 and commingled with the gas-free effluent from alkylation zone 4 via line 5 and passed to separation zone 6 for recovery of the desired components therefrom. By the utilization of the commingling step, the unreacted aromatic compound, monoalkylated aromatic compound and polyalkylated aromatic compound are fed directly to the separation zone for separation into the desired components as hereinabove described.

A preferred embodiment of the process of the present invention is shown as FIGURE 2. Line 20 contains the commingled etiiuents from the alkylation-transalkylation zones described hereinabove with reference of FIGURE l. The combined feed passes to fractionation column 21, a conventional fraetionator-distillation column or tower. In addition, recovered boron triuoride from the process may be introduced via line 22, if needed, into the column below the feed deck. This is utilized when boron compound impurities, hereinafter described, tend to form and accumulate on the trays of the column and in the reboiler tubes. The column is operated so that the desired monoalkylated aromatic compound in ladmixture with higher molecular weight polyalkylated aromatic compound passes via line 23 to further fractionation and recovery in, for example, a second fractionation column. The recovered unreacted `alkylatable aromatic compound passes overhead from column 2l in admixture with boron rifluoride through line 2d to overhead separator 25. Separator 25 is operated at conditions of temperature and pressure so that the boron trifluoride in admixture with the unreacted alkylatable aromatic compound may be removed via line 27 and passed to line 3l as hereinafter described. The unreacted alkylatable aromatic compound is Withdrawn from separator 2S through lines 26 :and 2S. Line 26 provides reflux to fractionation zone El and the remainder or net amount of the unreacted alkylatable aromatic compound passes via line 2% to stripper 29.

Stripper zone 29, labeled stripper is a countercurrent contacting zone, of conventional design, the size of which is varied depending upon the quantity of unreacted aromatic compound passed thereto and upon the quantity of stripping gas passed to a lower region thereof. In stripper 29, the unreacted aromatic compound furnished through line 2d ows downward in fa countercurrent manner to the ascending gases which are introduced thereto in a lower region thereof, for example, via line 3i). The unreact-ive gases and boron compounds with a iiuorine to boron mol ratio of at least 3.0 are separated from the unreacted aromatic compound and vented from .stripper 29 via line 31 where the boron trifluoride recovered from separator 25 and removed via line 27 passes in admixture to the reactors as hereinabove described. The stripped unreacted aromatic compound substantially free of boron cornpound-s with a uorine to boron mol ratio of at least 3.0 is withdrawn from the bottom of stripper 29 through line 32 and passed to treating zone 33, labeled treater.

Many suitable inorganic oxides which are substantially but not necessarily completely anhydrous are utilizable as treating agents in the process of this invention. They may be utilized in the form of granules, grains, powders, particles, spheres, balls, tubular shapes, etc. These compounds include such substances as alumina, silica, titanium dioxide, zirconium dioxide, chromia, zinc oxide, magnesia, calcium oxide, silica-alumina, silica-magnesia, silica-alumina-magnesia, silica-alumina-zirconia, chromiaalumina, alumina-boria, alumina-sodium meta-aluminate, silica-zirconia, etc. Of the above-mentioned inorganic oxides, substantially `but not completely anhydrous alumina is preferred, and particularly, synthetically prepared alumina of a high degree of purity consisting of substantially anhydrous gamma-alumina or substantially anhydrous theta-alumina is preferred.

In accordance with the process of the present invention, the removal of the boron compound impurities with a tiuorine to boron mol ratio of less than 3.0 from the As set forth hereinbefore, unusual problems are encountered in the commercial application of an alkylationtransalkylation process necessitating the utilization of the process of the present invention. Trace quantities of Water are sometimes encountered per se or as coordination compounds of boron triuoride including the hydrates of boron trifluoride including boron trifluoride monohydrate, boron triliuoride dihydrate, boron trifluoride trihydrate, etc. In addition to the hereinabove mentioned compounds, other compounds comprising boron, hydrogen, oxygen and fluorine, may be present as aforesaid, such as, for example, B(OH)2F, B(OH)F2, etc. Intermediate solid but volatile materials, such as (BOFL: polymers, where x may be from about 3 to 10 or more are also sometimes encountered. These com-pounds are also sometimes encountered in combination with each other, with water, or with boron tritluoride, as well as by themselves. It Will be appreciated by those Iskilled in the art that the foregoing list of compounds has by no means exhausted the total number of compounds that may form reversibly when water and boron halide are present in a luid lorganic process stream. Such compounds may be removed from the process by the process of the present invention.

Another preferred embodiment of the process of the present invention is shown as FIGURE 3. Line contains the commingled effluents from the alkylation-transalkylation zones described hereinabove with reference to FIGURE 1. The combined feed passes to fractionation column 4l, a conventional fractionator-distillation column or tower. ln addition, recovered boron triiluoride from the process may be introduced via line 42, if needed, into the column below the feed deck. This is utilized when boron compound impurities, hereinbefore described, tend to form and accumulate on the trays of the column and in the reboiler tubes. rhe column is operated so that the desired monoalkylated aromatic compound in admixture with higher molecular Weight polyalkylated aromatic compound passes via line 4T to further fractionation and The boron compounds with a fluorine to boron mol ratio unreacted aromatic compound containing the same is effected by contacting said aromatic compound stripped of boron compound impurities having `a liuorine to lboron mol ratio of Iat least 3.0 with .a substantially anhydrous inorganic oxide at a temperature of from about 0 C. or lower to abort 300 C. or higher, and preferably from about 20 C. to about 250 C. although the exact temt perature needed will depend on the particular aromatic compound to be puried. The treating step is usually carried out at a pressure of from about substantially atmospheric to about 200 atmospheres or more. The pressure utilized is usually selected to maintain the particularly l of at least 3.0 pass overhead from column 4l through line dit to overhead separator 4S. Separator 45 is operated at conditions of temperature and pressure so that these boron compounds may be removed via line 47. Separator i5 returns any unreacted aromatic compound carried overhead in admixture with said boron compounds through line 46. The unreacted alkylatable aromatic compound free of boron compounds with a fluorine to boron mol ratio of at least 3.0 is taken as sidecut from column 4l via line 48 and passed to treating zone 49, labeled treater. rfreater 49 is of the same type as treater 33 described in reference to FIGURE 2 and may also contain a substantially but not necessarily completely anhydrous inorganic oxide treating agent as hereinabove described to remove the boron compounds with a tluorine to boron mol ratio of less than 3.0. The unreacted alkylatable aromatic compound now substantially free of boron compound impurities is then removed from treater 49 through line Sti and passed to the reaction zones.

The following example is introduced for the purpose of illustration with no intention of unduly limiting the generally broad scope of the present invention. The alkylation-transalkylation flow scheme Was modified so that the separation zone included those components as shown hereinabove in FIGURE 2. ln the alkylation of benzene with a refinery olf-gas containing a minor quantity of ethylene utilizing a boron triuoride-modied substantially anhydrous inorganic oxide, namely boron triliuoride-modified substantially anhydrous gamma-alumina in both reaction Zones, the use of the stripper resulted in better than reduction of the boron and fluoride concentration in the benzene stream to the treater. The boron level after stripping was reduced to 8 p.p.m. (Wt.) and the fluorine to boron mol ration to 1.6. The stripping gas utilized was that unreactive part of the refinery offgas, that is, the olefin-free content of said off-gas. This stripping gas was then included with the boron trifiuoride recovered from the fractionation column and passed to the reactors with no harmful effect on either the alkylation or transalkylation reaction. A savings of 75% of the boron trifluoride normally utilized and a fourfold increase in the treating agent life, namely, substantially anhydrous alumina, was accomplished. Conversion of the benzene to ethylbenzene was maintained at about 100% until the run was completed. At the completion of this run, the alkylation-transalkylation iiow scheme was again modified so that the separation zone now included those components as shown hereinabove in FIG- URE 3. In the alkylation of benzene with a refinery off-gas containing a minor quantity of ethylene, utilizing a boron triuoride-modiiied substantially anhydrous inorganic oxide, namely, boron trifluoride-modied substantially anhydrous gamma-alumina in both catalyst zones, substantial reduction of the boron and trifiuoride concentration resulted when utilizing the sidecut. The boron level of the sidecut benzene was about ppm. (Wt.) and the tiuorine to boron mol ratio was about 1.0. This resulted in a further decrease in boron triiiuoride consumption and increased the treating agent life. The treating agent utilized was a substantially anhydrous alumina. ri`he conversion of benzene to ethylbenzene was maintained again at about 100% until the run was completed.

As can be readily seen from both operations, the unusual commercial problems encountered were overcome by the process of the present invention and, in addition, due to the decreased consumption of boron trifluoride and increased life of the treating agent while maintaining the desired conversion to a kylated aromatic compound, the process became more efficient and more economical.

I claim as my invention:

1. An improved process for the production of an aromatic compound which comprises alkylating an alkylatable aromatic compound with an olefin-acting compound in the presence of a catalytic amount of boron trifluoride in an alkylation reaction zone containing a boron triuoride-modied substantially anhydrous inorganic oxide, commingling the effluent of said alkylation zone with efiiuent from a transalkylation reaction zone as hereinafter set forth, passing the thus commingled effluents to a separation zone and therein separating unreacted aromatic compound containing boron compound impurities, desired monoalkylated aromatic compound, higher molecular weight polyalkylated aromatic compound and boron trifluoride, stripping from said unreacted aromatic compound boron compounds having a fluorine to boron mol ratio of at least 3.0, then contacting the stripped unreacted aromatic compound with a substantially anhydrous inorganic oxide to remove therefrom boron compound impurities having a fluorine to boron mol ratio of less than 3.0, thereafter recycling a portion of said unreacted aromatic compound to the alkylation zone, removing desired monalkylated aromatic compound as product from the process, passing said polyalkylated aromatic compound in admixture with boron tritiuoride and another portion of said unreacted aromatic compound free of boron compound impurities to a transalkylation zone containing boron triuoridemodified substantially anhydrous inorganic oxide and therein reacting the polyalkylated aromatic compound with unreacted aromatic compound, and recycling the efuent therefrom to said commingling step as aforesaid.

2. An improved process for the production of an aromatic compound which comprises alkylating an alkylatable aromatic compound with an olefin-acting compound in the presence of a catalytic amount of boron trifluoride in an alkylation reaction zone containing a boron triiiuoride-modied substantially anhydrous inorganic oxide, commingling the efliuent from said alkylation zone with etiiuent from a transalkylation reaction zone as hereinafter set forth, passing the thus commingled efiiuents to a first fractionation column, taking as bottoms from said column desired monoalkylated aromatic compound in admixture with higher molecular weight polyalkylated aromatic compound, passing said admixture to further fractionation in a second fractionation column, taking as overhead from said first column unreacted aromatic compound and boron trifluoride, separating said boron trifluoride from said unreacted aromatic compound, passing said unreacted aromatic compound to a stripper zone, countercurrently contacting said unreacted aromatic compound with stripping gas to remove boron compounds having a fluorine to boron mol ration of at least 3.0, passing stripped unreacted aromatic compound to a treating zone and therein contacting said stripped unreacted aromatic compound with a substantially anhydrous inorganic oxide to substantially free the same of boron compound impurities, having a iiuorine to boron mol ratio of less than 3.0 thereafter recycling a portion of said unreacted aromatic compound to the alkylation zone, passing the admixture of desired monoalkylated aromatic compound and undesired polyalkylated aromatic compound to a second fractionation column, removing overhead in said second fractionation column desired monoalkylated aromatic compound as product from the process, passing as bottoms from said second fractionation column polyalkylated aromatic compound and mixing the same with another portion of said unreacted aromatic compound and boron trifluoride, passing said mixture to a transalkylation zone containing boron trifluoride-modiied substantially anhydrous inorganic oxide and therein reacting the polyalkylated aromatic compound with unreacted aromatic compound, and recycling the effiuent therefrom to said commingling step as aforesaid.

3. The process of claim 2 further characterized in that said inorganic oxide is substantially anhydrous alumina.

4. An improved process for the production of an aromatic compound which comprises alkylating an alklatable aromatic compound with an olefin-acting compound in the presence of a catalytic amount of boron trifluoride in an alkylation reaction zone containing a boron triuoride-modied substantially anhydrous inorganic oxide, commingling the effluent from said alkylation zone with eiuent from a transalkylation reaction zone as hereinafter set forth, passing the thus commingled eliiuents to a first fractionation column, taking as bottoms from said column desired monalkylated aromatic compound in admixture with higher molecular Weight polyalkylated aromatic compound, passing said admixture to further fractionation in a second fractionation column, taking as overhead from said first column boron triuoride, taking as sidecut from said first column unreacted aromatic compound, passing said unreacted aromatic compound to a treating zone and therein contacting said unreacted aromatic compound with a substantially anhydrous inorganic oxide to substantially free the same of boron compound impurities, thereafter recycling a portion of said unreacted aromatic compound to the alkylation zone, passing the admixture of desired monoalkylated aromataic compound and undesired polyalkylated aromatic compound to a second fractionation column, removing overhead in said second fractionation column desired monoalkylated aromatic compound as product from the process, passing as bottoms from said second fractionation column polyalkylated -aromatic compound and mixing the same with another portion of said unreacted aromatic compound and boron triuoride, passing the resultant mixture to a transalkylation zone containing boron trifluoridemodified substantially anhydrous inorganic oxide and therein reacting the polyalkylated aromatic compound with unreacted aromatic compound, and recycling the efiiuent therefrom to said commingling step as aforesaid.

5. The process of claim 4 further characterized in that said inorganic oxide is substantially anhydrous alumina.

6. An improved process for the production of ethylbenzene which comprises alkylating benzene with ethylene in the presence of a catalytic amount of boron triuoride in an alkylation reaction zone containing a boron trifluoride-modied substantially anhydrous alumina, commingling the eflluent of said alkylation zone with effluent from a transalkylation reaction zone as hereinafter set forth, passing the thus commingled eluents to a separation zone and therein separating unreacted benzene containing boron compound impurities, desired ethylbenzene, higher molecular Weight polyethylbenzenes and boron trifluoride, stripping from said unreacted benzene boron compounds having a uorine to boron mol ratio of at least 3.0, then contacting the stripped unreacted benzene with a substantially anhydrous inorganic oxide to remove therefrom boron compound impurities having a uorine to boron mol ratio of less than 3.0, thereafter recycling a portion of said unreacted benzene to the alkylation zone, removing desired ethylbenzene as product from the process, passing said polyethylbenzenes in admixture with boron triiluoride and another portion of said unreacted benzene free of boron compound impurities to a transalkylation zone containing boron tritluoride-modified substantially anhydrous alumina and therein reacting the polyethylbenzenes with unreacted benzene, and recycling the eluent therefrom to said commingling step as aforesaid.

7. An improved process for the production of cumene which comprises alkylating benzene with propylene in the presence of a catalytic amount of boron tritluoride in an alkylation reaction zone containing a boron triuoride-modied substantially anhydrous alumina, commingling the eilluent of said alkylation zone with effluent from a transalkylation reaction zone as hereinafter set forth, passing the thus commingled efuents to a separation zone and therein separating unreacted benzene containing boron compound impurities, desired cumene, higher molecular weight polypropylbenzenes and boron trifluoride, stripping from said unreacted benzene boron compounds having a uorine to boron mol ratio of at least 3.0, then contacting the stripped unreacted benzene with a substantially anhydrous inorganic oxide to remove therefrom boron compound impurities having a luorine to boron mol ratio of less than 3.0, thereafter recycling a portion of said unreacted benzene to the alkylation Zone, removing desired cumene as product from the process, passing said polypropylbenzenes in admixture with boron triuoride and another portion of said unreacted benzene free of boron compound impurities to a transalkylation zone containing boron trifluoride-modiied substantially anhydrous alumina and therein reacting the polypropylbenzenes with unreacted benzene, and recycling the eluent therefrom to said commingling step as aforesaid.

8. An improved process for the production of butylbenzene which comprises alkylating benzene with a butene in the presence of a catalytic amount of boron triiluoride in an alkylation reaction zone containing a boron trifluoride-modified substantially anhydrous alumina, commingling the effluent of said alkylation zone with eluent from a transalkylation reaction zone as hereinafter set forth, passing the thus commingled efuents to a separation zone and therein separating unreacted benzene containing boron compound impurities, desired butylbenzene, higher molecular weight polybutylbenzenes and boron trifluoride, stripping from said unreacted benzene boron compounds having a uorine to boron mol ratio of at least 3.0, then contacting the stripped unreacted benzene with a substantially anhydrous inorganic oxide to remove therefrom boron compound impurities having a fiuorine to boron mol ratio of less than 3.0, thereafter recycling a portion of said unreacted benzene to the alkylation zone, removing desired butylbenzene as product from the process, passing said polybutylbenzenes in admixture with boron trifluoride and another portion of said unreacted benzene free of boron compound impurities to a transalkylation zone containing boron triuoride-modied substantially anhydrous alumina and therein reacting the polybutylbenzenes with unreacted benzene, and recycling the efluent therefrom to said commingling step as aforesaid.

9. An improved process for the production of ethylbenzene which comprises alkylating benzene with a refinery off-gas containing a minor quantity of ethylene in the presence of a catalytic amount of boron triiluoride in an alkylation reaction zone containing a boron triiluoride-modified substantially anhydrous alumina, commingling the etlluent of said alkylation zone with eluent from a transalkylation reaction zone as hereinafter set forth, passing the thus commingled effluents to a separation zone and therein separating unreacted benzene containing boron compound impurities, desired ethylbenzene, higher molecular Weight polyethylbenzenes and boron trifluoride, stripping from said unreacted benzene boron compounds having a uorine to boron mol ratio of at least 3.0, then contacting the stripped unreacted benzene with a substantially anhydrous inorganic oxide to remove therefrom boron compound impurities having a lluorine to boron mol ratio of less than 3.0, thereafter recycling a portion of said unreacted benzene to the alkylation zone, removing desired ethylbenzene as product from the process, passing said polyethylbenzenes in admixture with boron triuoride and another portion of said unreacted benzene free of boron compound impurities to a transalkylation zone containing boron triiluoride-modied substantially anhydrous alumina and therein reacting the polyethylbenzenes with unreacted benzene, and recycling the effluent therefrom to said commingling step as aforesaid.

References Cited by the Examiner UNITED STATES PATENTS 2,75 6,26 1 7/ 5 6 Fetterly 260-672 2,995 ,6 1 1 8/61 Linn et al. 260-672 3,126,421 3/ 64 Jones 260--671 ALPHONSO D. SULLIVAN, Primary Examiner. 

1. AN IMPROVED PROCESS FOR THE PRODUCTION OF AN AROMATIC COMPOUND WHICH COMPRISES ALKYLATING AN ALKYLATABLE AROMATIC COMPOUND WITH AN OLEFIN-ACTING COMPOUND IN THE PRESENCE OF A CATALYTIC AMOUNT OF BORRON TRIFLUORIDE IN AN ALKYLATION REACTION ZONE CONTAINING A BORON TRIFLUORIDE-MODIFIED SUBSTANTIALLY ANHYDROUS INORGANIC OXIDE, COMMINGLING THE EFFLUENT OF SAID ALKYLATION ZONE WITH EFFLUENT FROM A TRANSALKYLATION REACTION ZONE AS HEREINAFTER SET FORTH, PASSING THE THUS COMMINGLED EFFLUENTS TO A SEPARATION ZONE AND THEREIN SEPARATING UNREACTED AROMATIC COMPOUND CONTAINING BORON COMPOUND IMPURITIES, DESIRED MONOALKYLATED AROMATIC COMPOUND, HIGHER MOLECULAR WEIGHT POLYALKYLATED AROMATIC COMPOUND AND BORON TRIFLUORIDE, STRIPPING FROM SAID UNREACTED AROMATIC COMPOUND BORON COMPOUNDS HAVING A FLUORINE TO BORON MOL RATIO OF AT LEAST 3.0, THEN CONTACTING THE STRIPPED UNREACTED AROMATIC COMPOUND WITH A SUBSTANTIALLY ANHYDROUS INORGANIC OXIDE TO REMOVE THEREFROM BORON COMPOUND IMPURITIES HAVING A FLUORINE TO BORON MOL RATIO OF LESS THAN 3.0, THEREAFTER RECYCLING A PORTION OF SAID UNREACTED AROMATIC COMPOUND TO THE ALKYLATION ZONE, REMOVING DESIRED MONALKYLATED AROMATIC COMPOUND AS PRODUCT FROM THE PROCESS, PASSING SAID POLYALKYLATED AROMATIC COMPOUND IN ADMIXTURE WITH BORON TRIFLUORIDE AND ANOTHER PORTION OF SAID UNREACTED AROMATIC COMPOUND FREE OF BORON COMPOUND IMPURITIES TO A TRANSALKYLATION ZONE CONTAINING BORON TRIFLUORIDEMODIFIED SUBSTANTIALLY ANHYDROUS INORGANIC OXIDE AND THEREIN REACTING THE POLYALKYLATED AROMATIC COMPOUND WITH UNREACTED AROMATIC COMPOUND, AND RECYCLING THE EFFLUENT THEREFROM TO SAID COMMINGLING STEP AS AFORESAID. 